PROJECT SUMMARY Negative urgency, a tendency to rash action in the face of negative emotions, is one of the strongest personality predictors of alcohol and marijuana misuse (heavy use, intoxication, and the experience of consequences). In the face of strong negative emotions, people high on negative urgency are theorized to engage in impulsive behavior that is hyper-focused on relieving negative affect despite the long-term consequences, negatively reinforcing impulsive behavior. However, no research has tested whether individuals high on urgency actually behave more impulsively in the face of negative emotions, what situations might enhance or buffer this effect, or what role affect-driven impulsivity plays in the development of alcohol and marijuana misuse during young adulthood. The goal of the current study is to (Aim 1) characterize the within- person process of negative urgency (Aim 2) identify between and within person moderators of that process, such as alcohol-promoting situations and emotion regulation, and (Aim 3) test the role of EMA-assessed urgency in the development of alcohol and marijuana misuse over two years of young adulthood. Using a large (n = 500) sample of young adults (age 18 ? 22) who regularly use alcohol or marijuana recruited from the community, the proposed study will critically test this theory of urgency using an ecological momentary assessment design matched with longitudinal follow-ups, allowing us to characterize between individual differences in the within-person process of impulsive responses to negative emotions, and the situations and behaviors that may exacerbate or attenuate this link. Understanding the mechanisms by which personality may lead to substance misuse will provide novel targets of research as well as spur the development of more focused personality targeted interventions.